The invention relates to disposable garments, and more particularly, a pants-type diaper, and methods of producing such garments. Disposable diapers of the children's training pant type, or of the adult incontinence type, have generally been made with a standard fashion. The disposable garments are typically produced in a laid-flat blank format, with the blanks forming a continuous web of material. The final form of the diaper is achieved by folding the blanks in half, either before or after they are cut from the web of material. The blanks must also be sealed along the side edges to form the final diaper shape.
With such transversely produced products, the side seals or bonds are created in the form of a cross-directional weld, typically produced either ultrasonically or thermally. When the folded flats are run through a bonding unit, either before or after the flats are cut into individual flats, the edges are held out so that all layers of the web are welded together. This results in the formation of a butt seam or weld.
Butt seams are inherently weak because normal usage applies forces, called peel forces, to the bond, which are relatively damaging to the bond. Such forces focus along the leading edges of the bond formation and push outwardly from the bond seam. When the flats are welded together, the bonding process essentially is a destructive process. The small welded area is subject to a large peel force that tends to push apart the bonded edges. Thus, a more durable bonding process is desirable.
A more suitable and durable type of seam would be a lap seam. Typically overlaying or layering the edges of the materials to be bonded forms a lap seam, which subjects the garment edges to shear forces as opposed to peel forces. Such a design is advantageous because the forces are typically distributed over the entire bonded area as opposed to the edges of the bond. However, lap seams have not been previously used, as it is difficult in positioning an anvil and a sealing machine used in the bonding process in a manner that would allow formation of a lap seam.